adamatari, I think that some people just don't realize. I was like that.
I had very close friendships with girls, and hated when they started to date, and wanted to be around them all the time etc. etc.
I knew about gay people, and stuff, but it never clicked for me that I could be attracted to women. That was for other people, not me, and I'd just be a really good ally and stuff.
Some people do realize when they are younger, but others it takes a little longer, and that's okay. When I realized, I kept trying to be "normal." There's pressure in society, and I was afraid.